Effect of pulmonary function testing on the management of acute asthma

Routine pulmonary function testing has been recommended as part of the emergency department management of acute asthma despite the lack of evidence demonstrating the necessity for these measurements. The purpose of this study was to assess the physician's ability to estimate pulmonary function in patients with acute asthma and to determine the effect that pulmonary function testing has on patient management.

Emergency medicine physicians estimated pulmonary function in adult asthmatic patients prior to spirometry. The estimations and spirometry were repeated after 1 hour and again at discharge. The physicians noted their treatment plan before and after receiving the results of pulmonary function testing.

Ninety-eight patients were enrolled in the study. There was only moderate correlation between pretreatment estimates of pulmonary function and the actual value (r = .41). On average, physicians underestimated the degree of pretreatment airway obstruction (as percentage of predicted normal value) by 8.1 +/- 16.0 percentage points. Knowledge of the pulmonary function test results changed management in 20.4% of patients. The most common change was an alteration in the decision to continue treatment after 3 hours.

Physicians tend to underestimate the degree of airway obstruction in acute asthma, particularly on initial assessment. Since the availability of pulmonary function tests changes management in a significant number of patients, routine pulmonary function testing is recommended as part of the assessment and monitoring of acute asthma.